TS EAMCET · Physics · Magnetic Effects of Current
A non-conducting disc of radius \(R\) has surface charge density which varies with distance from the centre as \(\sigma(r)=\sigma_0\left[1+\sqrt{\frac{r}{R}}\right]\), where \(\sigma_0\) is a constant. The disc rotates about its axis with angular velocity \(\omega\). If \(B\) is the magnitude of magnetic induction at the centre, then \(\frac{B}{\mu_0 \sigma_0 \omega R}\) will be
- A \(\frac{3}{4}\)
- B \(\frac{4}{5}\)
- C \(\frac{5}{6}\)
- D \(\frac{6}{7}\)
Answer & Solution
Correct Answer
(C) \(\frac{5}{6}\)
Step-by-step Solution
Detailed explanation
Consider an elemental ring of radius \(r\) of thickness \(d r\) Charge on ring \(d q=\) Area of ring \(\times\) Charge density \(\Rightarrow \quad d q=(2 \pi r \cdot d r) \sigma\) \(\Rightarrow\) Current through ring, \(d i=\frac{d q}{T}\), as angular velocity of disc is…
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